Keyless Entry Signal Authentication via Intensity Fluctuation
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Solution Overview
Problem
Existing keyless entry systems are vulnerable to relay attacks, where fraudulent devices can mimic legitimate signals, making it difficult to distinguish between true and fraudulent request signals, especially as newer relay devices can transmit signals with intensity changes, rendering previous intensity change-based prevention methods insufficient.
Innovation Solution
A keyless entry device that transmits request signals with varying intensity levels, allowing the portable device to detect fluctuations in reception intensity, thereby differentiating between true and fraudulent signals, and calculates intensity change rates and time intervals to enhance authentication reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal intensity change is used to prevent relay attack, then relay attack prevention is improved, but fraudulent relay devices can mimic the intensity change pattern, making the prevention method insufficient
Solution Approach 1:
The request signal is divided into multiple sections with different intensity levels (first section with higher intensity, second section with lower intensity). This segmentation allows the system to detect not just any intensity change, but specific patterns of intensity changes across multiple sections, which fraudulent relay devices cannot easily reproduce due to signal attenuation
Solution Approach 2:
The patent changes the intensity level parameter of the request signal across different sections. By transmitting sections with varying intensity levels and having the portable device detect the reception intensity of each section, the system creates a unique signal pattern that can be verified. The portable device calculates intensity change rates between sections, and legitimate signals maintain specific relationships between these changes while relayed signals show abnormal patterns due to attenuation
2Measurement precision
If the vehicle-side device transmits request signals with different intensity levels in different sections, then the ability to detect fraudulent signals is improved, but the device complexity increases
Solution Approach 1:
The system dynamically adjusts the intensity level of request signal sections based on the distance between the vehicle and portable device. The vehicle-side device determines distance using reception intensity information, then sets appropriate intensity levels for different sections to ensure the intensity change pattern remains detectable even when attenuated by distance, optimizing both detection accuracy and power consumption
Solution Approach 2:
The system uses feedback from the portable device's reception intensity detection to verify signal authenticity. The portable device measures reception intensity of each section, calculates intensity change rates, and compares them against expected patterns. This feedback mechanism allows the system to distinguish legitimate signals from relayed signals without requiring complex hardware modifications
Data Source
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AI summary
A keyless entry device capable of easily distinguishing between a request signal from a fraudulent relay device and a request signal transmitted from a true vehicle-side device is provided. A vehicle-side device includes a vehicle-side control un it that controls transmission of a request signal and performs predetermined control when authentication is successful on th e basis of an answer signal, a portable device includes a port able-device control unit that detects reception intensity info rmation of the request signal transmitted from the vehicle-sid e device and transmits an answer signal based on the reception intensity, the vehicle-side control unit controls a vehicle-s ide transmission unit so that the vehicle-side transmission un it transmits the request signal including the determination si gnal having an intensity level different for each section, and the vehicle-side control unit or the portable-device control unit determines whether or not the request signal is a true si gnal on the basis of a fluctuation in the reception intensity in each section of the determination signal received by the po rtable device.